Casing perforating gun



F. I. ALEXANDER CASING PERFORATING GUN July 22, 1941.

Filed July 24, 1939 inventor: f7 linden flavor-nay.

Patented July 22, 194i UNITED, STATES PATENT OFFICE CASING PERFORATING GUN Ford I. Alexander, Whittier, Calif. Application July 24, 1939, Serial No. 286,181

12 Claims.

This invention relates generally to perforating guns for well casing and more particularly to improvements in the shooting bores and explosion chambers of perforating guns.

The conventional perforating gun for well 'casing comprises a cylindrical body formed in its sides with a plurality of screw-threaded sockets, into which are screwed barrels provided with pro- Jectile shooting bores. An explosion chamber is formed in the body back of each barrel, into In one form of the invention, the explosion chamber is contained within a cavity in the inner end of the breech plug. As will be evident, this in which the shooting bore may conveniently be made of substantially increased length.

A further object of the invention is to provide a perforating gun design affording enhanced inherent structural strength in the part or parts in which the shooting bore' and explosion chamber are formed.

A still further object of the invention is to provide an electrically fired perforating gun having an improved arrangement for the electric cable and an improved means for connecting the electric firing elements to the cable.

In one aspect of the invention, the shooting bore is formed in the gun body, instead of in an insert barrel, while the explosion chamber is formed in the inner end of a breech plug screwed within a socket sunk in the side of the gun body,, or in the inner end of the socket between the breech plug and the breech end of the shooting bore. With this improved construction, the shooting bore becomes at once of increased length, extending from the bottom of the socket sunk in one side of the gun entirely through the gun body to the muzzle which opens at the opposite side of the body. The bore being in the gun body proper, a stronger construction is afiorded. To increase the life of the shooting bore, it may, if desired, be furnished with a replaceable liner. The plug houses, or forms an abutment in back of, the firing chamber and powder charge, and contains the firing element or fuse. The explosion chamber and shooting bore are located within a relatively thick mass of metal, and the breech plug affords a strongtype of closure, so that an unusually sturdy construction is afforded.

novel type of breech plug is not necessarily limited to use in connection with a gun having a shooting bore in the main gun body.

The electric cable which ignites the fuses is preferably received within a spiral groove sunk in the outer surface of the body of the.gun and which passes in turn the outer ends of the explosion chamber plugs mounted in the gun body. Electrical connections are made from this cable to the fuse in each explosion chamber plug through a suitably packed duct formed in the plug.

The invention will be more fully understoo from the following detailed description of present preferred embodiments thereof, reference for this purpose being had to the accompanying drawing, in which:

Fig. 1 is a side elevation, with parts broken away, of a perforating gun in accordance with the invention;

Fig. 2 is a section taken on line 2-2 of Fig. 1; Fig. 2a is a view similar to Fig. 2, but showing a modified construction;

Fig. 3 is a section taken on line 3-: of Fig. 1;

and v Fig. 4 is a fragmentary view showing a modification.

Reference is now directed to the drawing, and

particularly to Figs. 1, 2 and 3. In Fig. 2a, which shows certain modified structure, members corresponding to members in Fig. 2 are identified by the same numerals but with the letter a adioined.

The cylindrical gun body is designated 'gener- I .ally at IU, said body being shown as provided at the top with a screw-threaded pin ll adapted for connectlon with a sub or other means, not illustrated, but which will be understood to be adapted for connection with the loweringline. Body I0 is provided with a plurality of horizontal, radially disposed shooting bores i2, spaced from one another longitudinally of and around the gun body. In the specific embodiment illustrated in Fig. 1, the shooting bores are spaced around the gun body by an interval of and while this arrangement is preferred, and the present invention lends itself especiallywell to such an arrangement, this is of course not to be understood as limitative of the invention considered in its broader aspects. side of the gun body in axial alinement with each of bores I2 is a socket ii, the inner end of Sunk into the socket.

which meets the inner end of bore l2, and is defined by an annular shoulder. I4. Socket I3 is furnished with screw-threads l5 extending inwardly from its outer end to a point which is preferably and typically approximately two thirds of its depth, as illustrated in thedrawing, thus leaving a straight walled inner sectionat i6. Preferably, this straight walled section l6 tapers or converges somewhat toward shoulder H, for a purpose later to be explained, and is so illustrated in Fig. 2, though in Fig. 2a the surface I60 joining the screw-threaded portion of socket i3a with shoulder Ila is not provided with such a taper, and in certain cases the construc- 1 tion of Fig. 20. may be satisfactory.

Screw-threaded within socket I3 is an explosion chamber plug or breech plug 20, the latter being externally screw-threaded as at 2| for engagement with threads i5, and having an inner end portion 22 adapted to seat against surface It, with its inner end 23 terminating just short of annular shoulder H. The outer surface 24 of this forward or inner end portion 22 of plug 20 is formed at the same angle as body surface l6, being therefore tapered complementarily to surface I6 in the instance of Fig. 2. In Fig. 2a, the plug 20a has an inner end portion 22:: of cylindrical shape, which slidably engages the cylindrical surface I60 at the inner end of the Formed in the inner, end of plug 20 is an explosion chamber 25, the depth of which is typically and preferably approximately one-third the length of plug 20. This chamber 25 is adapted to contain a powder charge 26. A frangible disk 21 is seated within a countersink 23 formed in the end of plug 20 and serves as a closure for the explosion chamber, sealing said chamber against external liquid pressure. A lead sealing ring 29 seated on annular seat I4 is engaged by the inner end 23 of plug 20 and by disk 21 when the plug is screwed h'ome within socket 13. In the instance of Fig. 2, the inner end 23 of the plug is in tight, sealing engagement with sealing ring 29 on seat II by the time or just prior to the time connected to fuse 31 extends through a duct 4 and enlarged packing gland bore 4| out through the outer end of the plug. This conductor 39 is preferably an enamel insulated copper wire. The packing gland for said wire consists of a packing ring 42, composed for example of rubber or the like, and a bushing screwed within the outer .portion of bore 4|, the bushing compressing ring 42 tightly around wire 39 and thereby effectively sealing against liquid. In the form of the invention illustrated in the drawing, fuse 31 is provided with a single electrical connection 39, and it will be understood that the outside shell of the fuse will in such case be electrically grounded to plug 20, the electrical circuit extending from conductor 39 through the fuse to its grounded external shell. The construction of the fuse and its ground may be conventional and no detailed explanation will be necessary. Of course,

its tapered surface 24 engages the tapered surface 16 of the socket. This provision assures a liquid tight seal for the explosion chamber, both the inner end 23 of the plug and the frangible disk 21 being pressed into sealing engagement with sealing ring 29.

A projectile is indicated at 30, positioned adjacent disk 21. The outer end or muzzle of bore I2 is preferably closed by a liquid seal 3 l Since plug 20 receives a considerable impact from the explosion within chamber 25, its screwthreaded connection with body If) must be adequate to withstand the stresses existing at such time. In the form of Fig. 2, a conventional V-thread is employed, of a pitch of eight threads to the inch. In Fig. 2a, a buttress thread is employed, as illustrated. Either type is deemed suitable, though of course any other appropriate threading or looking arrangement may .be employed if desired. V

In Fig. 2a, the shooting bore I20 is shown equipped with a replaceable liner 35, which is in a bore 33 opening to firing chamber 25, the in-,

net end of said fuse being immediately adjacent powder charge 28. An electrical conductor, 39

in any case in which it may not be desired to ground one side of the fuse to the gun body, it will be necessary to bring two conductors out from the fuse, both"'of which must be packed against fluid. Because of the greater ease of packing a single wire, however, the single wire arrangement is ordinarily preferred.

Fig.- 4 shows a modification in which the powder charge is. positioned within the socket between the breech plug and shooting bore, but not actually within the end portion of the plug. In this figure, in which members corresponding to members in Fig. 1 are identified by the same reference numerals but with the sub-letter b annexed, the powder charge 26b is positioned within a reduced inner portion 60 of socket l3b immediately adjacent frangible disk 21b. The inner end of lug 20b is positioned adjacent the powder charge, which may be in the form of a pellet, and has a shoulder 6! that engages a sealing disk 82 and compresses it against an annular shoulder 63 formed at the inner end of the portion 60 of socket l3b. This sealing disk, which may 'be composed of lead, effects a seal against pressure fluid leaking past threads llib. The provisions for the fuse 31b and its connecting lead may be substantially the same as in Fig. 1, and are so illustrated. I

Various electrical systems for energizing the fuses 31, either successively or simultaneously, may be employed. If the projectiles of the gun are to be fired successively, it is of course necessary that a separate conductor be run from a suitable switch or distributor to the fuse of each firing chamber, while if the projectiles are all to be fired simultaneously, the fuses may be connected either in series with or parallel across a single electric firing circuit, as is well understood. For simplicity, I have illustrated only the arrangement in which the projectiles are fired simultaneously by an electrical firing circuit across which the fuses are connected in parallel arrangement, though it will. be understood that either of the other arrangements may be substituted if desired. Thus. the electrical conductor 33 brought out through the duct in each of plugs 20 is electrically connected to an electrical cable 46,,which in this illustrative case consists of a single electrical conductor, covered with suitable insulation 46a (see Fig. 3). This conductor extends downwardly through a duct H in pin ll, said duct opening through the side wall of the cylindrical gun body at a point Just above the uppermost firing chamber socket l3, as indicated in Fig. 1. The electrical circuit above the upper end of the gun may'of course be conventional and is therefore not shown. This conin said socket, said plug having anexplosion ductor 46 is then received by a groove 48 sunk in, the outer surface of cylindrical body It; in the present illustrative embodiment, this groove is spirally arranged about body I and passes or intersects each of the sockets II in turn, in the arrangement clearly illustrated in Fig. l.

The outer end of each of plugs 20 is Provided with a plurality of notches 49 adapted to receive the conductor 46 where it crosses over, the

' made between each fuse conductor 39 and ,con-

ductor 48 by removing a portion of theinsulachamber opening to the inner end of said shooting tion' of conductor 46 and soldering conductor 39 thereto. The connection so made is then insulated in any suitable manner, as for instance by coating with shellac.

It will be understood that when conductor 46 is connected to a source of electrical current, the other side of which is grounded to gun body i0, electrical current will flow through each of fuses 31, thereby discharging powder charges 26 to expell the projectiles 30 from gun 'bores l2.

Attention is directed to the relatively long gun bore I2 resulting from the novel construction in accordance with the invention. This long bore results in sustaining the pressure back of the "projectile for a longer period of time before the projectile is expelled, with the result that higher projectile velocity and higher penetrating power are obtained. Attention is further directed to the fact that the explosion chamber and firing bore are located within a relatively thick mass of metaL'and that the breech plug releasably held within that mass is in itself of considerable mass and completes the enclosure of the explosion chamber, except at the discharge side thereof. At the same time, the area of the breech plug subjected to endwise pressure as the gun is fired is relatively small, so that the reactive force on the breech plug tending to drive it from its socket as the gun is fired is minimized. Thus it will be I seen that an unusually sturdy construction is afforded, such as will prevent any tendency to rupture of the parts as firing occurs. The tapered seat It for the tapered forward end portion of the explosion chamber or breech plug assures easy removability of the plug after firing. The explosion within the explosion chambers some times tends to expand the forward end portion of the plug somewhat, and without this provision, a certain binding may result making removal of the plug somewhat diflicult. The tapered construction of Fig. 2 avoids this difficulty, since the initial rotation of the plug results immediately in separating the tapered surfaces It and 24, following which the plug may be readilyv unscrewed from the socket.

It will beunderstood that the drawings and description are to be considered illustrative of and not restrictive on the broader claims appended hereto, since various changes in design, structure and arrangement may be made without departing from the spirit and scope of the invention or of the appended claims.

I claim:

1. A casing perforating gun comprising a gun body, a socket formed in a side of said gun body, a shooting bore in said gun body extending from the inner end of said socket through said gun body, and an explosion chamber plug mounted bore.

2. A casing perforating gun comprising a gun body, a screw-threaded socket formed in a side of said gun body, a shooting bore extending from the inner end of said socket through saidgun body, and an explosion chamber plug screwthreaded within said socket, said plug having an explosion chamber opening to the inner end of said shooting bore.

3. A casing'perforating gun comprising a gun body, a screw-threadedsocket formed in a side of said gun body, said socket terminating in an annular seating surface, a shooting bore extending from said annular seating surface through the gun body, an, explosion chamber plug screwthreaded within said socket, and a sealing ring mounted on said seating surface and adapted to be engaged by the inner end of said plug, said plug having an explosion chamber opening to the inner end of said shooting bore.

4. A casing perforating gun comprising a gun body, a screw-threaded socket formed in a side of said gun body, said socket terminating in an annular seating surface, a shooting bore extend.- ing from said annular seating surface through the gun body, an explosion chamber plug screwthreaded within said socket, said plug having an explosion chamber extending inwardly from its inner end, a frangible disk mounted adjacent the inner end of said plug and closing said explosion chamber, and a sealing ring seated on said annular seating surface and adapted to be engaged by said frangible disk at the inner end of the explosion chamber plug when said plug is screwed home in said socket.

5. A casing perforating gun comprising a gun body, a screw-threaded socket formed in a side of said gun body, said socket terminating in an annular seating surface, a shooting bore extending from said annular seating surface through the gun body, an explosion chamber plug screwthreaded within said socket, said plug having an explosion chamber extending inwardly from its inner end, a counter-sink in the end of said plug around said explosion chamber, a frangible disk mounted in said countersink with its outer surface flush with the end of the plug, and a sealing ring on said annular seating surface adapted to be-engaged by the inner end of the explosion chamber plug and by said frangible disk when said plug is screwed home in said socket.

6. A casing perforating gun comprising a gun body, a socket formed in a side of said gun body, said socket having an outer screw-thread section and an inner inwardly tapering surface, a shooting bore extending from the inner end of said socket through said gun body, and an ex-' plosion chamber plug having an outer screwthreaded section adapted for screw-threaded engagement with the screw-threaded section of said socket and an inner section having a taper complementary to and adapted to' seat on the tapered inner surface of said socket, said plug having an explosion chamber opening to the inner end of said shooting bore.

"I. A casing perforating gun comprising a gun body, a socket formed in a side of said gun body, said socket having an outer screw-thread section and an inner inwardly tapering surface, said inwardly tapering section terminating in an annular seating surface, a shooting bore extending from said annular seating surface through the gun body, an explosion chamber plug having an outer screw-threaded section adapted for screwthreaded engagement with the screw-threaded section of said socket and an inner section having a taper complementary to and adapted to 7 seas n the tapered inner surface of said socket, "said'plug having an explosion chamber opening to the"'inner end of said shooting bore, and a sealing ring on said seating surface engaged and "compressed by the inner end of said plug immediately'prior to engagement between the tapered section of the plug with the tapered seating surface in the socket. I

8. A casing perforating gun comprising a gun body, a screw-threaded socket formed in a side of said gun body, a shooting bore extending from the inner end of said socket through said gun body, an explosion chamber plug screw-threaded within said socket, said plug having an explosion chamber opening to the inner end of said shooting bore, and having a duct extending from said explosion chamber through the outer end of the plug, said duct 'being adapted to receive an electric fuse in a position adjacent said firing through the gun body, a groove formed in the surfa'ce'of the gun body extending around and lengthwise of the gun body so as to pass by the outer ends of said sockets in turn, an electrical cable received in said groove, explosion chamber plugs screw-threaded in said sockets, electrical 10. A casing perforating gun comprising a gun body, a socket formed in a side of said gun body. a shooting bore in said gun body extending from the inner end of said socket through said gun body, and a plug mounted in said socket, there being an explosion chamber within said socket between the inner end of said plug and the inner end of said shooting bore.

11. A casing perforating gun comprising a gun body, a socket formed in a side of said gun body, a shooting bore in said gun body extending from the inner end of said socket through said gun body, and a plug mounted in said socket, the inner end of said plug and the socket inwardly of said plug forming an explosion chamber.

12. In a casing perforating gun, a body having an exterior surface and having a breech plug socket extending inwardly from said surface, a shooting bore of lesser cross-sectional area than said socket alined with said socket and extending from the inner end of said socket through said body and opening through an opposite exterior surface on said body, said socket and shooting bore extending straight through said body from one of said exterior surfaces to the other, and a breech plug removably mounted in said socket in axiai alinement with said shooting bore and removable from said socket in a direction rearwardly from said shooting bore, said' breech plug having in its inner end portion an interior explosion chamber cavity opening to the breech end of the shootingbore and adapted to contain an explosive charge.

FORD I. ALEXANDER. 

